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Re: Cassandra: Inconsistent data on reads (LOCAL_QUORUM)

Mick, sorry I think I missed your following questions:


We saw this issue a couple of times a few years ago. That's why we introduced this change. Although at that time, it was on cassandra 1.x version. 

- Topology changes:

The only change we did was that we added nodes for 2 months. But that process finished 1 month ago. Since then we've run multiple repairs on the table. Other than that no other topology changes were done. 

From: Mick Semb Wever <mick@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, October 24, 2018 4:12:57 AM
To: user@xxxxxxxxxxxxxxxxxxxx
Subject: Re: Cassandra: Inconsistent data on reads (LOCAL_QUORUM)
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> Here's a bit more information:
> -Few rows in this column family can grow quite wide (> 100K columns)
> -But we keep seeing this behavior most frequently with rows with just 1 or two columns . The typical behavior is: Machine A adds a new row and a column. 30-60 seconds later Machine B tries to read this row. It doesn't find the row. So the application retries within 500ms. This time it finds the row.

You wrote a lot of useful info in your original post, sorry I missed
it in my first reply.
Only thing there that stands out, apart from short reads that Jeff's
already pointed out, is the use of `speculative_retry='ALWAYS'`. Has
there topology changes in your cluster recently?

Next step would be to try and repeat it with tracing.


Mick Semb Wever

The Last Pickle
Apache Cassandra Consulting

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